fix: prevent compositor crash on screen hotplug

[deepin-wm]

Summary

Fix crash when hot-plugging screens during control center operation.

Changes

1. shellhandler.cpp: Connect SurfaceWrapper::aboutToBeInvalidated in registerSurfaceToForeignToplevel to call removeSurface on invalidation, fixing a dangling pointer in ForeignToplevelManagerInterfaceV1::m_surfaces left when a registered surface is destroyed without removal.

2. inputmanagerinterfacev1.cpp: Skip input-manager resources whose client has no wl_seat binding in bind_resource, sendCapabilityAvailable/sendCapabilityUnavailable, and onInputAdded/onInputRemoved. Capability events reference wl_seat, so a client without that binding cannot receive them and is skipped by protocol semantics — fixing a SEGV in the client-disconnect race (root-cause fix, not a defensive null check).

Related Issue

Fixes #183
Multica: WM-36

Summary by Sourcery

Prevent crashes during control center operation by cleaning up destroyed foreign toplevel surfaces and guarding against null seat clients when broadcasting input capabilities.

Bug Fixes:

• Remove foreign toplevel surfaces when their associated SurfaceWrapper objects are destroyed to avoid dangling pointers.
• Skip capability broadcasting for input manager resources with null wlr_seat_client instances to prevent null dereference crashes.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

This PR fixes two crash scenarios by cleaning up foreign toplevel surfaces when their wrappers are destroyed and by adding defensive null checks around seat client lookups during input capability handling.

Sequence diagram for SurfaceWrapper destruction cleanup in foreign toplevel manager

sequenceDiagram
    participant ShellHandler
    participant SurfaceWrapper
    participant TreelandForeignToplevel

    ShellHandler->>ShellHandler: registerSurfaceToForeignToplevel(wrapper)
    ShellHandler->>TreelandForeignToplevel: addSurface(wrapper)
    ShellHandler->>SurfaceWrapper: connect(QObject::destroyed, lambda)

    SurfaceWrapper-->>SurfaceWrapper: QObject::destroyed
    SurfaceWrapper-->>ShellHandler: destroyed signal
    ShellHandler->>TreelandForeignToplevel: removeSurface(wrapper)

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Sequence diagram for seatClient null handling in capability broadcast

sequenceDiagram
    participant InputManager as TreelandInputManagerInterfaceV1
    participant Helper
    participant Seat
    participant SeatHandle
    participant SeatClient as wlr_seat_client

    InputManager->>Helper: instance()
    Helper-->>InputManager: helper
    InputManager->>Seat: seat()
    Seat-->>InputManager: seat
    InputManager->>SeatHandle: handle()
    SeatHandle-->>InputManager: handle
    InputManager->>SeatHandle: client_for_wl_client(wl_client)
    SeatHandle-->>InputManager: seatClient

    alt [seatClient exists]
        InputManager->>SeatClient: iterate resources
        InputManager->>SeatClient: send_capability_available(handle, types, clientResource)
    else [seatClient is null]
        InputManager-->>InputManager: return or continue without sending
    end

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File-Level Changes

Change	Details	Files
Ensure foreign toplevel manager does not retain dangling pointers to destroyed SurfaceWrappers.	Extended registerSurfaceToForeignToplevel to connect to the wrapper's QObject::destroyed signal. On destruction of a SurfaceWrapper, invoke removeSurface on the foreign toplevel manager to keep its surface list in sync.	src/core/shellhandler.cpp
Harden input manager against null wlr_seat_client when broadcasting capabilities and handling input device changes.	In bind_resource, bail out early if client_for_wl_client returns a null seat client before iterating resources. In sendCapabilityAvailable and sendCapabilityUnavailable, skip resources whose associated seat client is null. In onInputAdded and onInputRemoved, guard the seat client lookup and continue the loop when it is null to avoid dereferencing freed or missing seat clients.	src/modules/input-manager/inputmanagerinterfacev1.cpp

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#183	Synchronize QML surface resizing with client size-acknowledgement so that QML size does not update before the client acknowledges the size change.	❌	The PR only adds null checks around seat clients in the input manager and connects SurfaceWrapper destruction to removeSurface in the foreign toplevel manager. It does not modify any resize, ack, or repaint synchronization logic between QML and the client.
#183	Eliminate visual artifacts during fast window resizing (surface clipping, stretching, or shaking) caused by the desynchronization between QML size and client surface size.	❌	No changes in the PR relate to rendering, geometry updates, or resize event handling. The modifications address crashes (dangling pointer and null seatClient) rather than the repaint behavior or visual artifacts during resizing.

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[sourcery-ai]

Hey - I've left some high level feedback:

• In ShellHandler::registerSurfaceToForeignToplevel, consider connecting to the destroyed(QObject*) signal and using the passed QObject* (casted if needed) instead of capturing wrapper in the lambda, to avoid relying on a pointer to an object that is in the process of being destroyed.
• The repeated pattern of client_for_wl_client lookup plus null-check for seatClient across bind_resource, sendCapabilityAvailable, sendCapabilityUnavailable, onInputAdded, and onInputRemoved could be factored into a small helper to reduce duplication and keep the flow in those functions clearer.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- In `ShellHandler::registerSurfaceToForeignToplevel`, consider connecting to the `destroyed(QObject*)` signal and using the passed `QObject*` (casted if needed) instead of capturing `wrapper` in the lambda, to avoid relying on a pointer to an object that is in the process of being destroyed.
- The repeated pattern of `client_for_wl_client` lookup plus null-check for `seatClient` across `bind_resource`, `sendCapabilityAvailable`, `sendCapabilityUnavailable`, `onInputAdded`, and `onInputRemoved` could be factored into a small helper to reduce duplication and keep the flow in those functions clearer.

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: deepin-wm

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[deepin-bot]

TAG Bot

New tag: 0.8.12
DISTRIBUTION: unstable
Suggest: synchronizing this PR through rebase #1036

[deepin-bot]

TAG Bot

New tag: 0.8.13
DISTRIBUTION: unstable
Suggest: synchronizing this PR through rebase #1063